Navien Error Code E291: Cascade Communication Error
Warning: Your Navien boiler's cascade communication is experiencing an error, which may impact its performance and efficiency. It's safe to troubleshoot, but if the issue persists, contact a professional.
How to Fix Navien Code E291
- Check if the cascade module is securely connected and powered
- Ensure the module's configuration matches your boiler's settings
- If the issue persists, try resetting the boiler and the cascade module
How to Reset Navien Code E291
- Turn off the unit using the power button on the front panel.
- Turn off the gas supply valve.
- Turn off the circuit breaker supplying power to the unit. Wait 30 seconds.
- Restore power at the breaker, then open the gas valve.
- Turn the unit back on. If the error returns, the underlying issue needs repair.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Navien Error Code E291 Mean?
The E291 error on your Navien boiler indicates a cascade communication issue between the boiler and its optional cascade module. This error doesn't pose an immediate safety risk, but it's important to address it to maintain optimal system performance. The cascade module allows multiple boilers to operate together, and this error suggests there's a problem with this communication.
Common Causes
- Faulty cascade module or wiring
- Incorrect configuration or settings
- Power supply issue with the cascade module
- Interference from other electrical devices
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| Cascade module is connected and powered | Measure the voltage at the cascade module's power terminals | 12V DC |
| Voltage is within range | Inspect the wiring between the boiler and the cascade module for any damage or disconnections | No damage or disconnections |
Applicable Navien Models
Source Documentation
Referenced in 3 official Navien technical manuals.
| Manual | Page | Reason | Action |
|---|---|---|---|
| NFB-H Installation & Operation Manual | 116 | Return Temp. Exceeds Supply | Check for reversed piping. |
| Navien NFB-H Installation & Operation Manual | 116 | Return Temp. Exceeds Supply | Check for reversed piping. |
| Navien NHB-H Installation & Operation Manual | 119 | Return Temp. Exceeds Supply | Check for reversed piping. |
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Cascade Module | — | — | — |
Related Codes on Same Models
Other codes that affect the same Navien model families as E291.
| Code | Description | Severity |
|---|---|---|
| E001 | Ignition Failure | Warning |
| E003 | Abnormal Ignition | Warning |
| E004 | False Flame Detection | Warning |
| E012 | Flame Loss | Warning |
| E016 | Overheating | Warning |
| E030 | Exhaust Overheat Sensor | Warning |
| E031 | Inlet Thermistor Open/Short | Warning |
| E046 | Outlet Thermistor Open/Short | Warning |
| E047 | DHW Thermistor Open/Short | Warning |
| E060 | Fan Motor Abnormality | Warning |